Fluorescent dynamics of CsPbBr₃ nanocrystals in polar solvents: a potential sensor for polarity

Abstract

During synthesis, device processes, and applications of perovskite nanocrystals (NCs), there are usually inevitable interactions between perovskite NCs and polar solvents. To elaborately control the properties of perovskite NCs, investigating the effects of solvent polarity on perovskite NCs is thus highly important. Herein, fluorescent variations induced by different solvents into CsPbBr3 NCs solution are systematically studied. In this report, it is found that when CsPbBr3 NCs are treated with polar solvents, the fluorescence intensity decreases with a general redshift of fluorescence peak position. Moreover, the fluorescence quenching and peak position shift amplitude monotonously increase with the solvent polarity. Absorption spectra and fluorescent lifetime suggest that, with addition of polar solvents, the surface of NCs are destroyed and defect states are generated, leading to the fluorescent variations. Besides, dielectric constant of the solvent also increases with polarity, which may weaken the quantum confinement effect and decrease the exciton binding energy. We find the fluorescence may slightly blue shift if the emission of free carrier is strong enough with certain solvents, such as dimethylsulfoxide (DMSO). We also find the fluorescence intensity generally deceases to a stable state in 2 min, indicating quick interactions between CsPbBr3 NCs and solvents. However, water continuously quenches the fluorescence of CsPbBr3 NCs up to 72 h due to the poor miscibility between water and n-hexane. This work not only provides a comprehensive understanding on the fluorescent dynamics of CsPbBr3 NCs in polar solvents but also affords a potential fluorescent indicator for solvent polarity.

Simple and sustainable synthesis of perovskite-based optoelectronic material: CsPbBr3 nanocrystals via laser ablation in alcohol

“…The effects of different commercially available alcohols, used as solvent for the LASiS process, on the optical properties of CsPbBr 3 NCs colloidal solutions are investigated. Although in traditional bottom-up synthesis alcohols are usually found to be not beneficial for perovskite NCs, 25,26 here it is demonstrated that orthorhombic CsPbBr 3 nanocrystals with narrow FWHM down to 16 nm, long PL lifetimes up to 17.9 ns, and good PLQY up to 15.5% can be obtained by selecting the dielectric constant and polarity of the alcohol employed for the synthesis. The lower surface tension and higher vapor pressure of alcohols, compared to traditional high boiling toxic solvents used for LHP processing, can be exploited in sustainable and fast compatible processing.…”

“…CsPbBr 3 NCs by 2-step conversion were obtained by mixing a colloidal solution of PbBr 2 precursors NCs, synthesized via 3a). 25,35,36 laser ablation in alcohol (see Fig. S3 †), with an equimolar CsBr solution in EtOH.…”

“…Comparison of a) UV-Vis spectra, b) steady-state PL emissions, and c) time-resolved PL decays of CsPbBr 3 NCs synthesized by 1-step in-situ synthesis in different alcohols (PL profiles are normalized to the intensity of the respective absorption peak). The intensity-averaged lifetimes reported in (c) were calculated by three-exponential fit of the respective PL decays, following previous (the reported values are intensityaveraged lifetime values, see Figure 3 a) 25,35,36.…”

Optical Property and Stability of Lead‐Free Cs3Sb2Br9 Perovskite Microplatelets Prepared by a Solution Method

“…[18][19][20] Compared with the hybrid perovskites, all inorganic perovskites are attracting enormous attention owing to their advantages of simple preparation, low cost, and better stability. [21,22] Nevertheless, the stability of all inorganic perovskites without post-treatment is still not excellent enough for practical applications. [22] Moreover, the toxicity of Pb is also a crucial issue that limits their further applications.…”

“…[21,22] Nevertheless, the stability of all inorganic perovskites without post-treatment is still not excellent enough for practical applications. [22] Moreover, the toxicity of Pb is also a crucial issue that limits their further applications. [23][24][25] Therefore, currently, a lot of research work has been dedicated to the development of lead-free inorganic perovskites with good stability for optoelectronic device applications.…”